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In this study, the effects of Dy2O3/WS2 co-doping on magnetic properties and microstructure of Nd-Fe-B–sintered magnets were investigated. With WS2 addition, microstructure regulation and coercivity improvement were achieved in the Dy-containing magnets. The optimal magnetic performance was obtained in the 2 wt% Dy2O3/0.4 wt% WS2 co-doped magnets. The coercivity, remanence, and maximum energy product were 1727.1 kA/m, 1.211 T, and 286.5 kJ/m3, respectively. The coercivity was 10.5% higher than the WS2-free magnets, while there was no obvious change in the remanence and the maximum energy product. Relatively clear grain boundary phases were observed with smaller grain size. The average grain size of the co-doped magnets was 6.4 μm, which was about 1.6 μm smaller than the WS2-free magnets. More uniform Dy distribution was also obtained with the Nd2O2S phase formation. Besides, the W element likely precipitated at the grain boundaries. [ABSTRACT FROM AUTHOR]

In this paper, powder metallurgy (PM) H13 steels were investigated based on the characterisation of water atomised H13 powders. Vacuum sintering was carried out from 1150 to 1265°C for sintering densification. The relative density of the as-sintered sample reached to 95% and mechanical properties were released above 1200°C. To eliminate the residual pores, subsequent forging was performed. The relative density increased to above 99%. As the concentration of Si elements on the powder surface was higher than the nominal composition, there was Si segregation in the form of silicon oxides (1–3 μm). Although oxide particles such as SiO2 were inevitable, the mechanical performance of PM H13 steels was still comparable to that of ingot metallurgy products. The tempered PM H13 steels exhibited high tensile strength of 1460 MPa in YS, 1737 MPa in UTS and 8.7% in elongation. Besides, the impact toughness was as high as 14.7 J cm−2. [ABSTRACT FROM AUTHOR]